Riot Games have scheduled a maintenance for League of Legends at different morning hours of Wednesday, 29 August 2018, depending on the servers' time zones. The update will bring a batch of balance changes as well as Nunu & Willump rework.
Nunu & Willump might not replace the old Nunu immediately, but they will be added during patch 8.17 cycle. It shouldn't be long though as the most drastic changes are VFX, SFX, voiceover, models and textures, all of which have already been deployed to League of Legends clients. Gameplay changes should be easy enough to implement, barring a game breaking bug or two.
Speaking of which, Nunu & Willump's passive will now absorb the effects of the old Blood Boil, as they will increase an ally's attack speed after hitting an enemy champion, structure or large monsters. The passive attack speed boost will prioritise allies with the highest attack speeds, to make sure the bonus is not applied to a mage instead of a marksman.
Their Q will remain Consume and will function almost the same as the old one, since it will deal true damage to minions and monsters and heal Nunu & Willump. However, the heal will now increase with missing health and Consume can be used on enemy champions but it will deal magic damage and heal for less health.
Since Blood Boil was moved to the passive, W received a completely new ability - Biggest Snowball Ever! It will act somewhat like a mini Sion ultimate where the champion starts ramping up the speed, has lower control of turning and will knock enemy champions up on collision. The name is appropriate as the ability has ridiculous snowball potential with AP items, as it has 1.5 scaling. This means it will deal about 1400 damage with 700 AP.
Snowball Barrage will be Nunu & Willump's new E, which has a lot lower scaling. It will be primarily used as a tool to line up the perfect ultimate though, as it causes slow and root on enemy champions around Nunu & Willump.
The ultimate remains Absolute Zero, but with different scaling and an added shield for an extra layer of protection. It features a staggering up to 2.5 AP scaling and high base damage which means the champion will be able to decimate even tanks if he gets to channel it long enough.